Latex agglutination: an appropriate technology for the diagnosis of bacterial meningitis in developing countries

The epidemiology of meningococcal disease in India

OBJECTIVE

To undertake a review of the literature on the epidemiology of meningococcal disease in India, with a view to informing future control policies.

METHODS

We searched the PUBMED, EMBASE, Global Health, IMSEAR and MedIND databases for observational studies relating to the burden of endemic meningococcal disease in India, the occurrence and epidemiological characteristics of epidemics, and the prevalence of individual meningococcal serogroups.

RESULTS

The relatively few reports identified suggest that the incidence of endemic meningococcal disease in India is low, but that occasional epidemics of meningococcal disease have been recorded for at least 100 years. The larger epidemics have affected mainly the cities of northern India and have almost universally been caused by meningococci belonging to serogroup A. These epidemics have showed a few characteristics, including a marked seasonality, which are similar to those of epidemic meningococcal A disease in Africa.

CONCLUSIONS

New serogroup A-containing meningococcal conjugate vaccines are now being developed and reaching the market, including an affordable monovalent serogroup A vaccine manufactured in India, but intended primarily for use in Africa. These new tools may have a role in containing future Indian epidemics, but their usefulness is dependent on early identification of epidemics. This will require a functional disease surveillance system with adequate laboratory support throughout India.

Evaluation of polymerase chain reaction (PCR) for diagnosing Haemophilus influenzae b meningitis

A polymerase chain reaction (PCR) for detecting Hib in cerebrospinal fluid (CSF) was evaluated and compared with culture and a latex agglutination test (LAT) in a hospital-based prospective surveillance. We studied 107 children aged from 1 month to 12 years with a clinical and CSF profile suggestive of acute bacterial meningitis. CSF culture was performed on blood-chocolate agar by standard technique, LAT by a commercially available kit (Wellcogen) and PCR using total DNA extracted from CSF samples. Of 107 children, 79% had received one or more doses of injectable antibiotics. Hib was detected by culture in 14 cases, by LAT in 23 and by PCR in 37. All CSF samples that reveal Hib by culture or LAT had a PCR positive for Hib (sensitivity 100%). PCR also detected 14 additional cases of Hib meningitis which were not detected by culture or LAT. We conclude that PCR is a sensitive and specific diagnostic tool that may be valuable in a population with high pre-hospital antibiotic usage.

Nasopharyngeal carriage of Haemophilus influenzae

OBJECTIVE

Nasopharyngeal colonization of Haemophilus influenzae (H. influenzae) in young children may be important in developing countries.

METHOD

In this study, we screened school going children for carriage of H. influenzae. A total of 44 H. influenzae isolates out of a collection of 162 were characterized for biotypes, capsular serotypes and antibiotic resistance.

RESULTS

A significant proportion of H. influenzae (25/44) isolates were serotype b. High antibiotic resistance was observed against commonly administered antibiotics like ampicillin (79%), chloramphenicol (20%), trimethoprim sulfamethoxazole (84%) and erythromycin (95%). Comparison of antibiotic resistance profile of nasopharyngeal isolates was observed to be correlated with those of H. influenzae from disease.

CONCLUSION

Multidrug resistant nasopharyngeal H. influenzae in young healthy children may act as reservoir. Monitoring of antibiotic resistance among nasopharyngeal H. influenzae as a surrogate for invasive H. influenzae seems an attractive option.

Are Haemophilus influenzae infections a significant problem in India? A prospective study and review

It has been suggested Haemophilus influenzae serotype b (Hib) disease is uncommon in Asia. During 1993--1997, we conducted prospective surveillance of acute infections caused by H. influenzae in 6 academic referral Indian hospitals. The study included 5798 patients aged 1 month to 50 years who had diseases likely to be caused by H. influenzae; 75% of the patients were aged <5 years. A total of 125 H. influenzae infections were detected, 97% of which were caused by Hib. Of 125 isolates, 108 (86%) were from children aged <5 years, and 11 (9%) were from adults aged >18 years. Sixty-two percent of the patients had meningitis. The case-fatality rate was 11% overall and 20% in infants with Hib meningitis. Up to 60% of all isolates were resistant to chloramphenicol, ampicillin, trimethoprim-sulfamethoxazole, or erythromycin; 32% were resistant to >/= 3 antimicrobial drugs, but none were resistant to third-generation cephalosporins. These data suggest that available Hib vaccines will benefit Indian children.

Haemophilus influenzae disease in children in India: a hospital perspective

We review and summarize published information on diseases caused by Haemophilus influenzae in India and unpublished data from our center covering more than three decades. Since the mid-1950s H. influenzae has been the most common cause of pyogenic meningitis in children admitted to our hospital, accounting for one-third to one-half of cases. Information from other centers in India has been scanty; the lower frequency of isolation of Haemophilus in studies in some centers may be caused by unsatisfactory media and culture methods. The annual numbers of admissions for pyogenic meningitis in our hospital have been quite similar to the numbers of cases of poliomyelitis. Assuming that the similar numbers of children hospitalized with these two diseases indicate similar incidence rates in the community and taking into account the frequency of Haemophilus isolations in pyogenic meningitis, we estimate that there may be as many as 75 to 100 cases of meningitis caused by this organism per year per 100000 children <5 years of age. Although pneumonia caused by H. influenzae has been recognized in a few studies, information is too scanty to attempt the estimation of incidence. Pus-producing infections caused by Haemophilus are rare. Epiglottitis caused by Haemophilus does not seem to occur in India. In recent years we have found that most invasive Haemophilus infections are caused by H. influenzae type b (Hib); other types or untypable strains are infrequent. An increasing prevalence of resistance to chloramphenicol and ampicillin has been recognized in our center and elsewhere. Thus from a hospital perspective, primary prevention by using Hib vaccine seems to be a rational and beneficial intervention. Community-based studies to measure the disease burden of Hib are urgently needed for a more satisfactory assessment of the need for, and cost benefit of, Hib immunization of all infants.

Latex particle agglutination test in the diagnosis of Haemophilus influenzae type B, Streptococcus pneumoniae and Neisseria meningitidis A and C meningitis in infants and children

The knowledge of purulent meningitis etiology is essential in deciding the immediate therapy; in developing countries, however, the etiological agent identification does not reach 60% of the cases. A comparative study using the latex particle agglutination test (LPAT) in cerebrospinal fluid (CSF) for the diagnosis of meningitis due to Haemophilus influenzae type b, Streptococcus pneumoniae or Neisseria meningitidis A and C was carried out in Belo Horizonte MG, Brazil. CSF culture was used as a gold-standard. Two hundred and ninety-nine children, ranging from 3 months to 14 years of age, were included in the investigation. One hundred and forty-four presented a positive CSF culture for the above mentioned bacteria; the remaining presented meningitis due to other organisms (other bacteria or viral) or a normal CSF. The sensitivity and the specificity of LPAT was 95.7 and 100.0% for N. meningitidis C, 95.2 and 100.0% for H. influenzae type b and 86.5 and 100.0% for S. pneumoniae, respectively. When all three organisms were considered simultaneously, the sensitivity and the specificity was 93.0 and 100.0%, respectively. Taking into consideration a realistic estimate of disease prevalence in the community where the diagnostic test is being used, the positive predictive value and the posttest probability were estimated as 36.7 and 47.1% for children < 5 years and as 21.3 and 35.1% for children < 14 years of age, respectively. LPAT is a useful diagnostic test for meningitis due to the studied pathogens, especially in developing countries where laboratory facilities are limited.

Blood stained cerebrospinal fluid responsible for false positive reactions of latex particle agglutination tests

The accuracy of the latex particle agglutination test (LPAT) was assessed in blood stained cerebrospinal fluid (CSF) specimens from 166 paediatric patients, aged from three months to 13 years. A commercial LPAT kit was used to detect Haemophilus influenzae type b, Streptococcus pneumoniae, and Neisseria meningitidis A, B, and C soluble antigens. Culture of CSF specimens was used as the standard and all laboratory procedures were performed blind. The mean CSF erythrocyte count was 66,406 cells/mm3 in the cases and 11,560 cells/mm3 in the controls. The sensitivity and the specificity of LPAT were 83.8 and 94.0%, respectively, suggesting that LPAT is a useful diagnostic tool even in blood stained CSF specimens.